Java并发编程基础
- - 并发编程网 - ifeve.com并发是一种能并行运行多个程序或并行运行一个程序中多个部分的能力. 如果程序中一个耗时的任务能以异步或并行的方式运行,那么整个程序的吞吐量和可交互性将大大改善. 现代的PC都有多个CPU或一个CPU中有多个核. 是否能合理运用多核的能力将成为一个大规模应用程序的关键. 进程是以独立于其他进程的方式运行的,进程间是互相隔离的.
所用到的并发编程库
import java.util.concurrent.atomic.AtomicInteger; import java.util.concurrent.locks.ReentrantReadWriteLock;
package com.league.idgenerate; /** * * ID生成器接口, 用于生成全局唯一的ID流水号 * * @author Ivan.Ma */ public interface IdGenerator { /** * 生成下一个不重复的流水号 * @return */ String next(); }
package com.league.idgenerate; /** * ID生成器的配置接口 * @author Ivan.Ma */ public interface IdGeneratorConfig { /** * 获取分隔符 * @return */ String getSplitString(); /** * 获取初始值 * @return */ int getInitial(); /** * 获取ID前缀 * @return */ String getPrefix(); /** * 获取滚动间隔, 单位: 秒 * @return */ int getRollingInterval(); }
package com.league.idgenerate; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.atomic.AtomicInteger; import java.util.concurrent.locks.ReentrantReadWriteLock; /** * 默认的ID生成器, 采用前缀+时间+原子数的形式实现 * 建议相同的配置采用同一个实例 * @see IdGeneratorConfig * @author Ivan.Ma */ public class DefaultIdGenerator implements IdGenerator, Runnable{ private String time; private AtomicInteger value; private static final DateFormat FORMATTER = new SimpleDateFormat("yyyyMMddHHmmss"); private IdGeneratorConfig config; private Thread thread; private ReentrantReadWriteLock lock = new ReentrantReadWriteLock(); public DefaultIdGenerator(){ config = new DefaultIdGeneratorConfig(); time = DefaultIdGenerator.FORMATTER.format(new Date()); value = new AtomicInteger(config.getInitial()); thread = new Thread(this); thread.setDaemon(true); thread.start(); } public DefaultIdGenerator(IdGeneratorConfig config){ this.config = config; time = DefaultIdGenerator.FORMATTER.format(new Date()); value = new AtomicInteger(config.getInitial()); thread = new Thread(this); thread.setDaemon(true); thread.start(); } @Override public String next() { lock.readLock().lock(); StringBuffer sb = new StringBuffer(config.getPrefix()).append(config.getSplitString()).append(time).append(config.getSplitString()).append(value.getAndIncrement()); lock.readLock().unlock(); return sb.toString(); } @Override public void run() { while (true){ try { Thread.sleep(1000 * config.getRollingInterval()); } catch (InterruptedException e) { e.printStackTrace(); } String now = DefaultIdGenerator.FORMATTER.format(new Date()); if (!now.equals(time)){ lock.writeLock().lock(); time = now; value.set(config.getInitial()); lock.writeLock().unlock(); } } } }
package com.league.idgenerate; public class DefaultIdGeneratorConfig implements IdGeneratorConfig{ @Override public String getSplitString() { return ""; } @Override public int getInitial() { return 1; } @Override public String getPrefix() { return ""; } @Override public int getRollingInterval() { return 1; } }
测试类, 该类主要演示如何使用及相关测试功能代码,如下:
package com.league.idgenerate; import java.util.Collections; import java.util.HashSet; import java.util.Set; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import org.junit.Test; /** * 用法说明 * @author Ivan.Ma */ public class TestStandaloneIdGenerator { @Test public void test1(){ IdGenerator idGenerator = new DefaultIdGenerator(); System.out.println("--------简单测试------------------"); for (int i=0; i<100; i++){ System.out.println(idGenerator.next()); } } @Test public void test2(){ IdGenerator idGenerator = new DefaultIdGenerator(); //多线程测试 System.out.println("--------多线程测试不重复------------------"); Set<String> idSet = Collections.synchronizedSet(new HashSet<>()); ExecutorService es = Executors.newFixedThreadPool(100); for (int i=0; i<2000000; i++){ es.submit(() -> { String val = idGenerator.next(); if (idSet.contains(val)){ System.out.println("重复了: " + val); }else{ idSet.add(val); } }); } es.shutdown(); System.out.println("启用顺序关闭"); while(true){ if(es.isTerminated()){ System.out.println("所有的子线程都结束了!"); break; } try { System.out.println("子线程的任务还没运行完"); Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println("共生成: " + idSet.size() + "个"); } @Test public void test3(){ //测试单机性能 System.out.println("--------测试单线程性能------------------"); IdGenerator idGenerator2 = new DefaultIdGenerator(); long t1 = System.currentTimeMillis(); int total = 10000000; for (int i=0; i<total; i++){ idGenerator2.next(); } System.out.println("单线程生成" + total + "个ID共耗时: " + (System.currentTimeMillis() - t1) + "ms"); } //500个线程并发, 每个线程获取10000个ID @Test public void test4(){ //测试多线程性能 System.out.println("--------测试多线程性能------------------"); ExecutorService es1 = Executors.newFixedThreadPool(500); IdGenerator idGenerator3 = new DefaultIdGenerator(); long t1 = System.currentTimeMillis(); for (int i=0; i<500; i++){ es1.submit(() -> { int count = 0; while (count < 10000){ idGenerator3.next(); count++; } }); } es1.shutdown(); System.out.println("启用顺序关闭"); while(true){ if(es1.isTerminated()){ System.out.println("所有的子线程都结束了!"); break; } try { System.out.println("子线程的任务还没运行完"); Thread.sleep(200); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println("500线程,每个线程生成10000个序列号.共耗时: " + (System.currentTimeMillis() - t1) + " ms"); } @Test public void test5(){ System.out.println("--------测试生成的ID是否有时间滚动----------"); IdGenerator idGenerator = new DefaultIdGenerator(); for (int i=0; i<20; i++){ String id = idGenerator.next(); System.out.println(id); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } @Test public void test6(){ System.out.println("--------ID生成器的特殊设置相关----------"); IdGeneratorConfig config = new DefaultIdGeneratorConfig() { @Override public String getSplitString() { return "-"; } @Override public int getInitial() { return 1000000; } @Override public String getPrefix() { return "NODE01"; } }; IdGenerator idGenerator = new DefaultIdGenerator(config); for (int i=0; i<20; i++){ String id = idGenerator.next(); System.out.println(id); try { Thread.sleep(1000 * 1); } catch (InterruptedException e) { e.printStackTrace(); } } } }
运行结果如下:
--------简单测试------------------ 201602031124321 201602031124322 201602031124323 201602031124324 201602031124325 201602031124326 201602031124327 201602031124328 201602031124329 2016020311243210 2016020311243211 2016020311243212 2016020311243213 2016020311243214 2016020311243215 2016020311243216 2016020311243217 2016020311243218 2016020311243219 2016020311243220 2016020311243221 2016020311243222 2016020311243223 2016020311243224 2016020311243225 2016020311243226 2016020311243227 2016020311243228 2016020311243229 2016020311243230 2016020311243231 2016020311243232 2016020311243233 2016020311243234 2016020311243235 2016020311243236 2016020311243237 2016020311243238 2016020311243239 2016020311243240 2016020311243241 2016020311243242 2016020311243243 2016020311243244 2016020311243245 2016020311243246 2016020311243247 2016020311243248 2016020311243249 2016020311243250 2016020311243251 2016020311243252 2016020311243253 2016020311243254 2016020311243255 2016020311243256 2016020311243257 2016020311243258 2016020311243259 2016020311243260 2016020311243261 2016020311243262 2016020311243263 2016020311243264 2016020311243265 2016020311243266 2016020311243267 2016020311243268 2016020311243269 2016020311243270 2016020311243271 2016020311243272 2016020311243273 2016020311243274 2016020311243275 2016020311243276 2016020311243277 2016020311243278 2016020311243279 2016020311243280 2016020311243281 2016020311243282 2016020311243283 2016020311243284 2016020311243285 2016020311243286 2016020311243287 2016020311243288 2016020311243289 2016020311243290 2016020311243291 2016020311243292 2016020311243293 2016020311243294 2016020311243295 2016020311243296 2016020311243297 2016020311243298 2016020311243299 20160203112432100 --------多线程测试不重复------------------ 启用顺序关闭 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 所有的子线程都结束了! 共生成: 2000000个 --------测试单线程性能------------------ 单线程生成10000000个ID共耗时: 1972ms --------测试多线程性能------------------ 启用顺序关闭 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 子线程的任务还没运行完 所有的子线程都结束了! 500线程,每个线程生成10000个序列号.共耗时: 1605 ms --------测试生成的ID是否有时间滚动---------- 201602031124431 201602031124432 201602031124433 201602031124434 201602031124435 201602031124436 201602031124437 201602031124438 201602031124439 2016020311244310 2016020311244311 201602031124441 201602031124442 201602031124443 201602031124444 201602031124445 201602031124446 201602031124447 201602031124448 201602031124449 --------ID生成器的特殊设置相关---------- NODE01-20160203112445-1000000 NODE01-20160203112445-1000001 NODE01-20160203112446-1000000 NODE01-20160203112447-1000000 NODE01-20160203112448-1000000 NODE01-20160203112449-1000000 NODE01-20160203112450-1000000 NODE01-20160203112452-1000000 NODE01-20160203112453-1000000 NODE01-20160203112454-1000000 NODE01-20160203112455-1000000 NODE01-20160203112456-1000000 NODE01-20160203112457-1000000 NODE01-20160203112458-1000000 NODE01-20160203112459-1000000 NODE01-20160203112500-1000000 NODE01-20160203112501-1000000 NODE01-20160203112502-1000000 NODE01-20160203112503-1000000 NODE01-20160203112504-1000000
从该性能来看, 可以使用在高并发的场景, 欢迎大家来拍砖!